Precision feeler apparatus for grinding machines



April 28, l1925.

M. MAAG PnEcIsIoN FEELER APPARATUS Fon GRINDING MACHINES Filed Jan. 2l.1921 Patented Apr. 28, 1925.

UNITED STATES PATENT ol-Fica max Mana, or ZURICH, SWITZERLAND, AssIeNonor oNFfHALr 'ro THE FIRM HAAG-ZAHNnDEn a MASCHINEN A.G., or ZURICH,SWITZERLAND.

PRECISION EELER APPARATUS FOR GRINDING MACHINES.

implication fusa January 21, 1921. serial No. 439,011.

To all 'whom t may con-cem:

Be it knownthat L MAX MAAG, a citizen of the Republic of Switzerland,residing at |Zurich, Hardstrasse 219, Switzerland, have gertains to makeand use the same, reference eing had to the accompanying drawing, and toletters or figures of reference Imarked thereon, which form a part ofthis specification. i

Various devices are already known whereby the feed motion of grindingdiscs may be interrupted or signals operated when a piece has beenground down to a desired degree, 20 this being accomplished by means ofa feeler which constantly touches the blank during the operation,thereby nearing the axis of rotation as the blank is ground down untilcontacts influenced directly or indirectly by the feeler becomeconnected. These usually act by closing one or more electric circuitsoperating either the above mentioned devlce for the mterruption of thefeed motion or the aforesaid si als.l The degree of precision of thesedevices is in many cases insufficient, as the instant of connection ofthe contacts is to a certain degree uncertain because of the constant aplication of the feeler against the moving b ank. Also because theoperation of the mechanical or electrical parts of the interruptin orsignal devices cannot be maintained su ciently uniform, the operation ofthe said devices takes place either too early or too late: The wear ofthe feeler constantly applied against the blank constitutes anothersource of error, as well as the frequentlyobserved corrosion of thecontacts arising from sparking caused by vibration due to the constantapplication of the feeler against the revolving blank, whereby theelectric. circuit is constantl opened or closed from the rst moment otil the interrupting or signal device becomes operative. y

The present invention relates to improvements 1n the above mentioneddevices, by which the aforesaid disadvantages may be avoided. The feeleraccording to the invention is not constantly in touch with the blank,but only at certain intervals. For

contact uninstance, the feeler may contact with the work -for a shortmoment only after each movement of the grinding disc along the work.: Itis thus possible to minimize the wear ofthe feeler and the corrosion ofthe contacts. `According to a further feature of the invention, thecircuit which iis closed by 4the connection of-the feeler-contacts isnot used directly for the operation of the interrupting or signalingdevice, but serves to operate a relay which in its turn actuates theinterrupting or signalling device. The interposition of such a`relay-causes the mechanical or electrical action which has to beaccomplished by the electricl circuit closed by the feeler contacts toremain constant. The operation of'the signal .or interrupting deviceAtherefore takes place only at a certain constant intensity ofapplication of the feeler contacts which causes a certain current to Howthrough the relayf circuit and does not depend solelyon the actualmaking and breaking of the connection.` The range of the' contacts`between the firstf touch and the mpment of definite operation of thede- :vice is subdivided, whereby the degree of precisionof the feeler iscorrespondingly increased. At the first light touch, the electrical`resistance between the contacts is so high that the passage of acurrentstrong enough to actuate the relay is prevented. The saidresistancedecreases rapidly, howeverfwiththe increasing intensity ofapplication and allows more current to pass. The relay is not actuateduntil the pressure between the contacts is sufficient for a certaincurrent to pass. l

The relay enters into action sooner or later according to forcenecessary to move it. In order to grind down various similar blanksexactly to the same degree, it is necessary that the force to actuatethe relay should remain constant, 'so' that an equally -course berealized in many different ways.

The accompanying drawings show, an example of a precision feeleraccording to the blank, is periodically brought towards the latter bymeans of a solenoid each time the blank' has passed the grinding discand is released immediately after touching it. 4The force necessary toactuate the relay is main.- tained constant by means of an inclined flaprotatabl mountedl about its lower edge, which aphas to be swung over itsdead point by means of 4a. small magnet disposed 1n the circuit of thefeeler contacts, where-- upon the said fiap in tilting forward closesvanother circuit actuating the interrupting or signalling device.

The accompanying drawings show by way of example an arrangement of thiskind, in which t-wo contacts are provided, the. two electricI circuitsactuating relays each of which serves respectively to operate one flapof constant resistance whereby further circuits are closed which lightup signal lamps. In these drawings: l

Fig. 1 is a section through the feeling device with signal apparatus andsupport.

Fig. 2 shows'the device seen from above, partly in section; l

Fig. 3 is a view of the signals;

Fig.`4 illustrates in a diagrammatic manner a perspective view of thedevice showing the electric connections;

A. support 1 on which the parts of the feeler mechanismare mounted'isfixed to the work carrying table of the grinding machine so that the endof a feeler bar or rod 4 may contact with the work being ground. Witheach reciprocation of the work and table past the wheel, a. contact 62on the table touches a corresponding contact on a lever 61 so that thesolenoid of the feeler device is momentarily energized.

The support 1 carries two outer casings 2 and 3 of which the irstcontains the feeling device with the electric contacts and the solenoid,and the second the relays and signal device. The outer head 6 of thefeeler 4 is pressed at certain intervals against the blank 7, byenergizin the solenoid thereby compressing the ligt spring 8, whichserves to return the feeler to its initial position away from theblankas soon as the current travers ing the solenoid is interrupted. Thefeeler Y is slidably mounted in sleeves 9 and 10 carried in the casingand is fitted with a plston 11 co-operating with the, casing cylinder 12so as to form an air cushion, a sorbing any shocks due to the movementof the feeler. The feeler rod is fitted with a cross piece 13 on whichthe two contacts 14 and 15 are attached by means of diiferent-iallyadjustable micrometer screws 16 and 17. The opposing contacts 22 and 23are insulated in the support 1. Contact 22 is displaceable against theaction of a spring 27. The Contact carrier 26 is pressed against nut 29by means of spring 27 and plate 28, and is pushed back resiliently bythe movement of the feeler after touching the contacts. v Contacts 14and 22 are so-ca1led pre-contacts, 15 and 23 the final contacts, theyare preferably adjusted in such a manner that the precontacts touch1/10() mm. before .the final-contacts.

A perfectly air tight movable rubber sleeve y rod 4. The spring 8 issupported against disc 34 which closes the casing 32,v All parts areenclosed in the dust-proof hood 18. The two relays 40 and 41 with signallamps 42 and 43 and iaps 44 and 45- are disposed inside casing 3situated below casing 2. One of the two flaps is provided for thepre-contact, the other for the final contact. A lever 46 or 47respectively rotatably mounted on pivot 48, is situated between eachrelay and flap, one end of said lever being attracted by the relay `whenthe circuit is closed, the other end fitting the somewhat inclined flapyin such a manner thatthelatter tilts over its upper dead point and fallson to contact 50 `or 51 respectively, thus establishing a circuitthrough lamp 42 o1' 43 respectively, the signal being rendered visibleby the falling over of the fla-p.

When the blank is sufficiently ground, the solenoid circuit isinterrupted by means of switch 61 (Fig. 4) being out of contact withContact 62, spring 8 then returns the feeler 4, and preandfinal-contacts are separated from each other thus interrupting the relaycircuits so that the levers 46, 47 are respectively drawn back bysprings 52, 53.

The flaps can then be recocked by means of milled knobs 54 and 55 thusbreaking the lamp circuit after which the dev'ce is in position foroperating upon another blank of the same size as the first.

The'perspective view of Fig. 4 shows the electric circuits. Conductor 64is led from the battery 60 over switch 61, actuated'by the reciprocatingslide of the machine, to contact 62, then through coil 5 of thesolenoid, to fixing .screw 63, which clamps the goes through relay 41and final contacts 23 and 15.` The third and fourth subcircuits go fromthe battery through the signal lamps 42, 43 respectively, contacts 50,51 respectively, flaps 44, 45 respectively and through casing andconductor 65, back to the battery.

l To initially set tlie feeler mechanism in cooperative position on astandard form of cylindrical grinding machine, a blank or gage of thepredetermined finished dimension to be ground is placed inoperativeposition on -the work supporting means ofthe grinding machine and thefeeler diamond 31 on the feeler rod 4 moved to engage the cylindricalsurface of this gageLThis movement of the feeler mechanism maybeaccomplished by means, of adjusting screws which preferably are of theform d'sclosed in my copending applicationl 439,012, filed on even dateherewith. The contact carrying lever 61 is then manually moved to closecontact to be ground is withthe member 62 so that an electric circuit isformed continuously energizing the solenoid 5. This holds the feelerdiamond 31 in its extreme position toward the work axis. By positioningthe body member of 'the feeler mechanism by adjustment of thepositioning screws as above indicated', the mechanism may be set so thatthe final conta'ct between members 15 and 23 is closed at anypredetermined diameterat which point the mechanism is. in position foroperation upon blanks of the same size as that used as ga e. W'igth thefeeler mechanism adjusted as above described, the grinding operation maybe started by traversing the tool past the work which preferably may bedone by means of traversing the lslide on which the contact member 62 ismounted. `As this slide is reciprocatedy so that the part of the worktraversed past the wheel or grinding disc, the contacts 62 and 61 aremomentarily closed by this movement of the This traversing past thegrinding noid 5 and thus moves the feeler diamond 31 toward the work,after which the contact between members 61 and 6 2 is opened by furthermovement of the slide at eacli time -the spring 8 withdraws the diamond31 from engagement with the rotating work.

This momentary energizin of the solenoid 5 advances the feelervdiamond31 toward the work and as long as the work being operated on is aboveits predetermined size and for which the mechansm is adjusted the.

nals separately and successively operated by relay circuits," including""the solenoidsv 40 and 41 are not energized and therefore the signals 42and 43 are not operated. As

soon as the grinding has proceeded to such a point that the work isalmost ground to itsl final predetermined size, movement of the eelerrod 4.and its diamond 31 is sufificient to close the contactbetweenmembers 14 and 22. This operates one of the relay circuits.including the solenoid 40 and also l operates the signal 42. Furtherreciprocatory movement of the slide and continued grinding reduces thesize of the Work still` further until it is down toits final precisewhich the work may be removed and anewv blank inserted in position.

I claim:

1. A precision feeler apparatus for rinding machines, in combination, ane ectric circuit, means adapted'to close said circuit at eachreciprocation of the work carrying slide of a grinding machine, a feelermechanism, means to ymomentarily advance said feeler mechanism towardthe work, relay circuits, means adapted to close said circuits wlien.the movement of the feeler ex'- ceeds a predetermined amount, andindedependent signals successively operated by the closing of said relaycircuits. f

2. A precision eeler apparatus for grinding machines, in combination, anelectric circuit, means adapted to close said circuit at eachreciprocation of the work carrying slide of a grinding machine, a feelermecha nism, meansto momentarily advance said feeler toward the work, twoindependent relay circuits, means adapted to close said circuits, whenthe movement-.sof the feeler exceeds predetermined dierent amounts,I andsignals separately and successively op# erated by the closing of each ofsaid relay f circuits.

3. A precision feeler apparatus for grinding machines, in combination, afeeler rod, means adapted to` advance said rod toward the work beingground, relay circuits, means adapted to close said circuits by movementof said :Eeeler more than predetermined amounts, -and signalssuccessively operated by the closing of said relay circuits.

4. A recision eeler apparatus for grinding mac ines, in combination, afeeler rod, means adapted to advance said rod toward the-work beingground, independent relay Eircuits, means adapted to close said circuitsY predetermined different amounts, and sigthe closing of each of saidrelay circuits.

5. A precision feeler apparatus for grinding machines, in combination, afeeler, means adapted to advance said feeler into` contact with theblank for 4a short time at certain intervals, a-.lrelay, means adaptedto actuate said relay by a constant force, said relay being actuated byelectric means upon movement lof the feeler, and a signal deviceactuated by the relay and electrically con! nected to the latter.

6. A precision feeler apparatus, in .combination, a feeler of the rodtype, means adapted to momentarily advance said feeler into contactwith' and away from theblank at certain intervals, a solenoid, means ton energize said solenoid to effect the movesaid feeler into'contact withthe blank for' a short time at certain intervals, a solenoid adapted toeffect the movement ofthe feeler towards the blank, a spring operativelyconnected to said feeler and adapted t0 effect the movement of thelatter away from th'e blank, a relay adapted to be actuated by aconstant force, a switch operated by parts of the machine tool on whichthe blank is machined, a contacting device actuated by the feeler, asignal lamp, a hinged flap actuated by said relay. a source otelectricity. an electric main circuit between the source of electricity,said switch and said solenoid, an electric sub-circuit connected inparallel t'o said main circuit and comprising said source ofelectricity, said relay and said contacting device, and an electricsub-circuit arranged in parallel to said main circuit and compris'- Aingsaid source of electricity, said signal lamp and said Hap. '8. Aprecision feeler apparatus, in combination, a' eeler displaceablyarranged in its axial direction, means adapted to bring said feelerintocontact with the blank for a short time at certain intervals, asolenoid adapted to effect the movement of said feeler towards theblank, a spring operatively connected to said feeler and adapted toeffect the movement of the latter away from the blank, a final contactdevice operated by said feeler, a pre-contact device operated by saidfeeler, a relay electrically connected to the final contact device, twoindependent signal devices, means loperated by the first mentioned relayand electrically connected to one signal device, and second meansoperated by the second relay and electrically connected to a secondsignal device.

9. A precision feeler apparatus, in combination, a feeler displaceablyarranged in its axial direction, means adapted to bring said 'flaps andsaid lamps and closed by the tilted flaps, and a secondy casing in whichsaid relays, flaps, signal lamps and contacts are arranged.

l0. A precision feeler apparatus, in conibination, a feeler displaceablyarranged in its axial direction, means adapted to bring said feeler intotouch with the blank for a short time at certain intervals, including asolenoid adaptedto effect the movement of said `feeler towards theblank, a spring operatively connected to said feeler and adapted toeffect the movement of the latter away from the blank, an adjustablefinal Contact .device operated by said feeler, an adjustable'pre-contact device operated by said feeler,

said two contact devices being so adjusted relatively to each other,that the pre-contact device is actuated at the beginning of the laststep of machining the blank and the final contact device at the finishof said step, arelay, means connecting said relay electrically to thefinal contact device` a second relay, means connecting said relayelectrically to the pre-contact device, a first signalling deviceoperated by the first mentioned relay, and indicating the finish of themachining of the blank,'a second signalling device operated by thesecond relay and indicating the last step of machining the blank. Intestimony that I claim the foregoing as my invention, I have signed myname.

MAX MAAG.

